Preoperative increase in neuromuscular jitter and outcome following surgery for faecal incontinence

Manometric, sensorimotor, and neurophysiologic evaluation of anorectal function

With advances in diagnostic technology, it is now accepted that in the field of functional bowel disorders, symptom-based assessment is unsatisfactory as the sole means of directing therapy. A robust taxonomy based on underlying pathophysiology has been suggested, highlighting a crucial role for physiologic testing in clinical practice. A wide number of complementary investigations currently exist for the assessment of anorectal structure and function, some of which have a clinical impact in patients with functional disorders of evacuation and continence by markedly improving diagnostic yield and altering management. The techniques, limitations, measurements, and clinical use of manometric, sensorimotor, and neurophysiologic tests of anorectal function are presented.

Neurophysiological testing in anorectal disorders

The neurophysiological techniques currently available to evaluate anorectal disorders include concentric needle electromyography (EMG) of the external anal sphincter, anal nerve terminal motor latency (TML) measurement in response to transrectal electrical stimulation or sacral magnetic stimulation, motor evoked potentials (MEPs) of the anal sphincter to transcranial magnetic cortical stimulation, cortical recording of somatosensory evoked potentials (SEPs) to anal nerve stimulation, quantification of electrical or thermal sensory thresholds (QSTs) within the anal canal, sacral anal reflex (SAR) latency measurement in response to pudendal nerve or perianal stimulation, and perianal recording of sympathetic skin responses (SSRs). In most cases, a comprehensive approach using several tests is helpful for diagnosis: needle EMG signs of sphincter denervation or prolonged TML give evidence for anal motor nerve lesion; SEP/QST or SSR abnormalities can suggest sensory or autonomic neuropathy; and in the absence of peripheral nerve disorder, MEPs, SEPs, SSRs, and SARs can assist in demonstrating and localizing spinal or supraspinal disease. Such techniques are complementary to other methods of investigation, such as pelvic floor imaging and anorectal manometry, to establish the diagnosis and guide therapeutic management of neurogenic anorectal disorders.

Single-fiber electromyography correlates more closely with incontinence scores than pudendal nerve terminal motor latency

BACKGROUND

The investigation of fecal incontinence is important in deciding the most appropriate treatment. The presence of neuropathy has been shown to affect surgical outcomes adversely. Latency studies are of dubious value in assessing neuropathy; needle electromyography is the gold standard test. The relationship between these two tests and the symptoms of fecal incontinence has not been studied.

METHOD

A cohort of 57 patients underwent neurologic and symptom assessment using latency studies, concentric and single-fiber electromyography, and symptom assessment using the Cleveland Clinic Scoring System.

RESULTS

There was a significant correlation between left mean fiber density and Cleveland Clinic Scoring (correlation: 0.32, P = 0.02) but not between right or left latency studies.

CONCLUSION

Single-fiber electromyography gave relevant results that could be obtained easily on modern equipment. Latency values were not reliable.

Diagnostic testing in fecal incontinence

Fecal incontinence is a common problem that disproportionately affects women and the elderly and has a significant impact on the quality of life. Incontinence is often multifactorial. Anorectal manometry, anal endosonography, magnetic resonance imaging, pudendal nerve latency, and electromyography provide morphologic and physiologic assessments of the internal and external anal sphincters, rectal motor and sensory function, rectal compliance, and rectoanal reflexes. This information, in concert, provides clues to the pathophysiology of fecal incontinence and may help to guide medical, surgical, or biofeedback therapy. These tests have also been used to assess the effectiveness of the therapeutic modalities. No data are available on the cost-effectiveness of diagnostic testing in fecal incontinence. Newer techniques, including electrophysiologic testing and morphologic imaging of the anorectum, are being pursued.

The role of electrophysiology in the evaluation of incontinence and prolapse

PURPOSE OF REVIEW

Apart from histopathology, electrophysiological methods are the only tests to reveal neuromuscular involvement in the absence of gross anatomical lesions. They have played a major role in establishing the neuromuscular lesion due to vaginal delivery as a risk factor for incontinence and pelvic organ prolapse, but there is no consensus on the usefulness of different methods. It is timely to reevaluate their validity, and their role in urogynecology.

RECENT FINDINGS

The most important development is the move towards standardization of the diagnostic approach, based on computer assisted quantified techniques of concentric needle electromyography. Studies using less operator biased techniques have confirmed subtle pelvic floor muscle changes in parous women. Reports on usefulness of different tests as predictors of treatment outcome are controversial.

SUMMARY

Standardization of concentric needle electromyography strengthened the position of this test as practical and informative. Neuromuscular changes following vaginal delivery have been reconfirmed, but the usefulness of particular electrophysiological tests in the individual patient needs to be further researched. Valid clinical neurophysiological methods remain valuable as research tools for incontinence and prolapse pathophysiology.

Clinical neurophysiology and electrodiagnostic testing of the pelvic floor

This article summarizes our current understanding of the neuroanatomy and neurophysiology of the pelvic floor. The electrodiagnostic evaluation of the pelvic floor muscles and external anal sphincter, including pudendal nerve conduction studies, sacral reflexes, and needs EMG is presented. The discussion reviews the test methodology, the strengths and limitations of each test, and their clinical utility. The authors have tried to critically review the objective evidence to support the use of electrodiagnostic tests in the evaluation and management of pelvic floor disorders. The reader will have a better understanding of the rationale, methodology, clinical utility, and potential pitfalls for each of the commonly used neurophysiological tests of the pelvic floor.